1. Field of the Invention
The present invention relates to a vehicle manual transmission, and more particularly to the one having 6 shift stages for a forward travel and 1 shift stage for a reverse travel.
2. Description of Related Art
There has conventionally been known the one disclosed in Japanese Patent No. 2543874 as a vehicle manual transmission (hereinafter referred to as “M/T”) having plural shift stages for a forward travel and 1 shift stage for a reverse travel. In this type of M/T, an input shaft that forms a power transmission system with an output shaft of an engine, an output shaft that forms a power transmission system with drive wheels, and 2 intermediate shafts (a first intermediate shaft and a second intermediate shaft) are supported by a housing so as to be parallel to one another and so as to be capable of rotating.
Drive gears for the plural shift stages for the forward travel are coaxially fixed to the input shaft in such a manner that they cannot make relative rotation. Driven gears of some of the plural shift stages, which are always meshed with the drive gears of the above-mentioned some of the plural shift stages for the forward travel (e.g., plural shift stages at the lower speed), are arranged coaxially to the first intermediate shaft so as to be capable of making relative rotation. A first final drive gear is coaxially fixed to the first intermediate shaft in such a manner that it cannot make a relative rotation.
Similarly, driven gears of the remaining plural shift stages, which are always meshed with the drive gears of the remaining plural shift stages (e.g., the plural shift stages at the higher speed) of the plural shift stages for the forward travel, are coaxially arranged to the second intermediate shaft so as to be capable of making relative rotation. A second final drive gear is coaxially fixed to the second intermediate shaft in such a manner that it cannot make a relative rotation.
A final driven gear, which is always meshed with the first and the second final drive gears, is coaxially fixed to the output shaft in such a manner that it cannot make relative rotation. When the driven gear, corresponding to the shift stage for the forward travel selected through a driver's operation by a shift lever, is fixed to the intermediate shaft, to which the driven gear is mounted, in such a manner that it cannot rotate relative to the intermediate shaft, a speed reducing ratio (=ratio of the rotation speed of the input shaft to the rotation speed of the output shaft) corresponding to the selected shift stage for the forward travel is acquired when a vehicle travels forward.
Further, a drive gear for the reverse travel is coaxially and integrally fixed to the first-speed driven gear arranged at the first intermediate shaft. The driven gear for the reverse travel, which is always meshed with the drive gear for the reverse travel, is coaxially arranged to the second intermediate shaft so as to be capable of making a relative rotation. When the driven gear for the reverse travel is fixed to the second intermediate shaft so as not to be capable of making a relative rotation, which is executed corresponding to the selection of the reverse travel through the driver's operation to the shift lever, the second intermediate shaft inversely rotates, whereby the vehicle can be backed.
As described above, in the M/T of this type, the drive gear for the reverse travel and the driven gear for the reverse travel are respectively arranged at the first and the second intermediate shafts. Therefore, the M/T of this type does not need a rotation shaft (a third rotation shaft) exclusively used only for arranging the gear for the reverse travel. Additionally, the driven gears for the plural shift stages for the forward travel are arranged separately to the first and the second intermediate shafts. Therefore, compared to the case in which all driven gears for the plural shift stages for the forward travel are coaxially arranged to a single intermediate shaft, the total length of the M/T in the axial direction can be reduced. Accordingly, a compact M/T having a short length in the axial direction can be obtained.